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How a single star can reshape an entire galaxy

Phys · · 666 words · By Leiden University

Researchers from Leiden University used computer simulations to demonstrate that small changes in the position of a single star can lead to significant structural differences in a galaxy over time. The study explains how the 'butterfly effect' influences galactic modeling and resolves a paradox regarding the simultaneous smooth and chaotic behavior of galaxies.

open_in_new Read the original article: https://phys.org/news/2026-05-star-reshape-entire-galaxy.html

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Propaganda Score
confidence: 100%
Low risk. This article shows minimal use of propaganda techniques.

fact_checkFact-Check Results

10 claims extracted and verified against multiple sources including cross-references, web search, and Wikipedia.

info Single Source 6
help Insufficient Evidence 2
check_circle Corroborated 1
cancel Disputed 1
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“New research from Leiden University shows that [astronomers who simulate galaxies do not always get the same result, even when they start from identical conditions] is not a flaw, but a consequence of how galaxies behave—and how they are modeled.”
SINGLE SOURCE
The claim is explicitly supported by a web search result titled 'How a single star can reshape an entire galaxy', but no other independent news sources or academic references corroborate this specific research finding from Leiden University.
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wikipedia NEUTRAL — Leiden University Medical Center (Dutch: Leids Universitair Medisch Centrum) or LUMC is the university hospital affiliated with Leiden University, of which it forms the medical faculty. It is located …
https://en.wikipedia.org/wiki/Leiden_University_Medical_Cent…
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wikipedia NEUTRAL — Leiden University (abbreviated as LEI; Dutch: Universiteit Leiden) is a public research university in Leiden, Netherlands. Established in 1575 by William, Prince of Orange as a Protestant institution,…
https://en.wikipedia.org/wiki/Leiden_University
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wikipedia NEUTRAL — Leiden University Libraries is the set of libraries of Leiden University, founded in 1575 in Leiden, Netherlands. Holdings include some five million volumes, one million e-books, ninety thousand e-jo…
https://en.wikipedia.org/wiki/Leiden_University_Library
+ 3 more evidence sources
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“The computer simulations by Tetsuro Asano and Simon Portegies Zwart (Leiden Observatory) will soon be published in Astronomy & Astrophysics and are available now on the arXiv preprint server.”
SINGLE SOURCE
While web results confirm that Tetsuro Asano and Simon Portegies Zwart publish in Astronomy & Astrophysics, there is no specific evidence in the provided results confirming the current availability of this specific simulation paper on arXiv or its imminent publication date.
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web search NEUTRAL — Ripples spreading across the Galactic disc: Interplay of direct and indirect effects of the Sagittarius dwarf impact Asano, Tetsuro; Fujii, Michiko S.; Baba, Junichi; Portegies Zwart, Simon; Bédorf, J…
https://tetsuroasano.com/publications/
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web search NEUTRAL — Multi-physics simulations using a hierarchical interchangeable software interface. by. Simon Portegies Zwart; Steve McMillan; Arjen van Elteren; Inti Pelupessy; Nathan de Vries. Publication date.
https://archive.org/details/arxiv-1204.5522
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web search NEUTRAL — Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics.
https://www.aanda.org/articles/aa/abs/2025/08/aa53816-25/aa5…
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“The researchers created hundreds of models of Milky Way-like galaxies: flat disks of stars, embedded in a large, invisible cloud of dark matter that holds the system together.”
SINGLE SOURCE
The specific detail about creating 'hundreds of models' of Milky Way-like galaxies for this specific study is found only in the 'How a single star can reshape an entire galaxy' source.
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web search NEUTRAL — Using data from the Hubble Space Telescope, scientists have developed this simulation of the head-on collision of our Milky Way galaxy and the Andromeda gala...
https://www.youtube.com/watch?v=4disyKG7XtU
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web search NEUTRAL — Milky Way might be a rotating body of a huge number of stars, held together by gravitational forces akin to the Solar System but on much larger scales.[83]: 15 The resulting disk of stars would be see…
https://en.wikipedia.org/wiki/Milky_Way
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web search NEUTRAL — The researchers created hundreds of models of Milky Way-like galaxies: flat disks of stars, embedded in a large, invisible cloud of dark matter that holds the system together.
https://phys.org/news/2026-05-star-reshape-entire-galaxy.htm…
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“In each experiment, they ran two almost identical simulations, differing by just one tiny detail—for instance, a small shift in the position of a single star. Over time, that slight difference grows into visible structural changes: the spiral arms develop differently and the central bar rotates in another way.”
SINGLE SOURCE
The specific experimental setup (differing by one star) and the resulting structural changes are detailed only in the 'How a single star can reshape an entire galaxy' source.
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web search NEUTRAL — In spiral galaxies, the spiral arms do have the shape of approximate logarithmic spirals, a pattern that can be theoretically shown to result from a disturbance in a uniformly rotating mass of stars.
https://en.wikipedia.org/wiki/Galaxy
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web search NEUTRAL — Minor changes in the position of a single star can lead to significant structural differences in simulated galaxies, demonstrating that galactic evolution is highly sensitive to small perturbations.
https://phys.org/news/2026-05-star-reshape-entire-galaxy.htm…
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web search NEUTRAL — It is very difficult to count the number of stars in the Milky Way from our position inside the galaxy. Our best estimates tell us that the Milky Way is made up of approximately 100 billion stars. The…
https://imagine.gsfc.nasa.gov/science/objects/milkyway1.html
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“In many simulations, gravity at very small distances is "softened" to keep calculations stable and manageable.”
CORROBORATED
The use of gravitational 'softening' to maintain stability in simulations is confirmed by multiple independent sources: the specific article, a StackExchange astronomy discussion, and a technical paper on gravitational softening effects.
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web search NEUTRAL — Gravitational softening is a numerical trick introduced in particle simulations to avoid too close encounters that would otherwise result in unrealistic motion of particles.In other words, the chosen …
https://astronomy.stackexchange.com/questions/50106/what-is-…
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web search NEUTRAL — Generally, the use of gravitational softening lowers the expo-nential growth rate of spiral modes. Therefore, strongly softened N-body simulations may risk ‘losing’ some of these modes as their growth…
https://biblio.ugent.be/publication/8605616/file/8605617.pdf
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web search NEUTRAL — In many simulations, gravity at very small distances is "softened" to keep calculations stable and manageable.The degree of chaos observed depends on how gravitational interactions are modeled, partic…
https://phys.org/news/2026-05-star-reshape-entire-galaxy.htm…
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“Some features always appear, such as the formation of a central "bar" of stars, which emerges at roughly the same time in all simulations.”
SINGLE SOURCE
While sources discuss the general formation and evolution of stellar bars in galaxies, none of the provided evidence confirms that the bar emerges at 'roughly the same time in all simulations' for this specific study.
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web search NEUTRAL — The disc galaxy sample. Bar formation and evolution. Characterising the formation of stellar bars. Episodes of bar formation in galactic discs. The central stellar dominance of bar forming galaxies.
https://arxiv.org/pdf/2508.14626
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web search NEUTRAL — We find that barred galaxies tend to have lower Toomre Q values at the time of their formation, while we do not find a difference in the gas fraction of barred and unbarred populations when controllin…
https://www.researchgate.net/publication/389662436_Bar_forma…
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web search NEUTRAL — The Galactic Center is the barycenter of the Milky Way and a corresponding point on the rotational axis of the galaxy.[1][2] Its central massive object is a supermassive black hole of about 4 million …
https://en.wikipedia.org/wiki/Galactic_Center
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“the Milky Way becomes unpredictable after about a million years”
SINGLE SOURCE
The specific claim that the Milky Way becomes unpredictable after a million years is a direct quote from Portegies Zwart in the 'How a single star can reshape an entire galaxy' source; it is not found in general Wikipedia or other search results.
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wikipedia NEUTRAL — The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from star…
https://en.wikipedia.org/wiki/Milky_Way
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wikipedia NEUTRAL — Milky Way is a brand of malt-flavored milk chocolate-covered confectionery snacks manufactured and marketed by Mars Inc. since 1923. Created by Frank Mars, it was his first chocolate bar product. Ther…
https://en.wikipedia.org/wiki/Milky_Way_(chocolate_bar)
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wikipedia NEUTRAL — Sagittarius A*, abbreviated as Sgr A* ( SADGE-AY-star), is the supermassive black hole at the Galactic Center of the Milky Way. Viewed from Earth, it is located near the border of the constellations S…
https://en.wikipedia.org/wiki/Sagittarius_A*
+ 3 more evidence sources
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“the age of the Milky Way (about ten billion years)”
DISPUTED
The claim states the age is 'about ten billion years'. However, a specific 'Space' fact sheet lists the age as '13.6 billion years', creating a contradiction in the provided evidence.
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wikipedia NEUTRAL — The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from star…
https://en.wikipedia.org/wiki/Milky_Way
menu_book
wikipedia NEUTRAL — Milky Way is a brand of malt-flavored milk chocolate-covered confectionery snacks manufactured and marketed by Mars Inc. since 1923. Created by Frank Mars, it was his first chocolate bar product. Ther…
https://en.wikipedia.org/wiki/Milky_Way_(chocolate_bar)
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wikipedia NEUTRAL — Sagittarius A*, abbreviated as Sgr A* ( SADGE-AY-star), is the supermassive black hole at the Galactic Center of the Milky Way. Viewed from Earth, it is located near the border of the constellations S…
https://en.wikipedia.org/wiki/Sagittarius_A*
+ 3 more evidence sources
help
“Two simulations may end up looking different—with different spiral arms or a differently oriented bar—but both still remain recognizable as spiral galaxies.”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to support or refute this specific claim about the visual outcomes of the simulations.
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“T. Asano et al, The exponential growth of infinitesimal perturbations in the long-term evolution of simulated galaxies, Astronomy & Astrophysics (2026). On arXiv DOI: 10.48550/arxiv.2604.12053”
INSUFFICIENT EVIDENCE
No evidence was found in the provided search results to verify the existence of this specific paper title, DOI, or the 2026 publication date.
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.